"Re-setting" Geometry : scale, rotation etc.

I’m new to blender and here is what I don’t understand:
I have made a model of a room in order to create perspectives and rendered views of this interior space.
I created my room(s) from scratch so the dimensions are set from the start to my specs.

I then found 3d objects - such as tables, chairs, couches to add to my room.
These are often in different units and scaling is required to bring them to their proper dimensions in my room/ scene.
Also many are constructed in different coordinate systems: for example a table was created by its owner on it’s side and has been flipped right-side up so that the z is the height - so a rotation is applied for it to be “standing up”.

If I keep the inherited settings there are odd consequences: for example to make the table taller I need to scale the x rather than z. If objects are parented this only adds to the confusion. Figuring out what will happen with modifiers, such as an array is totally confusing.

How can I “re-set” the geometry? so that, for example, a table that measures 1x1 by 0.5 height ,x-y by z, in my scene is such at scale 1 to the scene coordinates?
In CAD software (which is familiar to me) I would “explode” the block(object) retaining its deformations and then make a new block out of it from the parts, based on the curent coordinate system…

-Christos

Ctrl+A in object mode (or Object / Apply mensu) to apply scale/rotation, or scale mesh in edit mode rather than object mode to keep current object scale.
Depending on original file format, check the import settings

Richard you are not just a moderator… you’re Blender-God-all-mighty.

Thank you